Chemotaxis occurs during a number of physiological events including angiogenesis, embryonic development, wound healing, immune defense, and the establishment of neuronal circuits. Accordingly, eukaryotic chemotaxis has been a topic of key interest in cell biology and pathophysiology. The objective of our research is to explore a long-standing conundrum in the field: How do cells break symmetry to initiate cell migration? To address this question, we will focus on two signaling modules that remain uncharacterized: Feedback and Crosstalk. Experimental dissection of these modules has proven inherently challenging, because their signaling operation in cells is local (sub-cellular) and rapid (second-to-minute) on top of their intimate intra- and inter-module relationships. The experimental perturbation of component molecules thus must be restricted to precise spatial domains and be faster than the signaling events. However, most tools used to probe signaling events are generally slow (minute- to-day) and global (supra-cellular) in their effects, limiting their usefulness. We previously developed a new generation of molecular tools that allows for Rapid, Inducible and Specific Perturbation (RISP) of various proteins in living cells. In order to decipher the kinetics and dynamics of molecular networks within the modules with high spatio-temporal resolution, we employ two different approaches: 1. operating the RISP in microfluidic device and 2. improving the present RISP by using synthetic photo- chemistry knowledge. These experimentations will allow us to determine whether and how the elementary signaling modules are integrated to orchestrate an intricate symmetry breaking process. A better understanding of the chemotaxis promises therapeutic advancements for cell migration-related diseases. Our unique approach for probing cellular dynamics will also provide a general-and-powerful methodology that has the potential to significantly extend conventional methods such as RNA interference and pharmacology. PUBLIC HEALTH RELEVANCE: Due to its significant involvement in biological processes, cell migration contributes to disease progression in cancer and arthritis, while its impairment leads to anomalous tissue development or regeneration. Our unique perturbation approach can be a powerful strategy for not only dissecting the molecular mechanisms, but also interfering with these cell migration-related diseases.